JPS60515A - Positioning device - Google Patents

Abstract

PURPOSE:To prevent self-oscillating vibrations and perform highly stable positioning, by providing a circuit which detects a deviation from a target value of output displacement and another circuit which delays the output signal of the circuit for a fixed time and reducing a speed loop gain by means of an operation complete signal. CONSTITUTION:A digital target value 21 is connected to an up-down counter 7 which is operated by a positional pulse signal 27 and the deviation signal of the output of the counter 7 is inputted into a motor 2 through a DA converter 8, log amplifier 9, and power amplifier 1. Under this condition, a speed feedback signal 29 is supplied to the input side of the power amplifier 1 and the positional pulse signal 27 is also supplied to the input side through a speed pulse generating circuit 6 and gain reducing circuit 11. The circuit 11 is operated by means of an operation complete signal 25 which is the output signal of a delay circuit 13 of a time Td which is actuated by signals 23 and 24 outputted through a deviation detecting circuit 12. By reducing a speed loop gain by means of the signal 25, self-oscillating vibrations caused by a speed pulse can be prevented from occurring.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a positioning device, and particularly to a positioning device that performs velocity feedback using a pulse train signal having a frequency proportional to velocity.

[Background of the invention]

In a positioning servomechanism using a motor, the response of the system can be improved by feeding back a speed signal. Conventionally, as a means for this purpose, as shown in FIG. 1, a means has been often used that uses a tachogenerator (speed generator Ja) 3 and feeds back a signal proportional to the speed of the motor 2 to the preamplifier 1 of the motor drive circuit. Ta. However, according to this method, in addition to the tachogenerator 3, it is necessary to separately use a means 4 (for example, a synchro, resolver, or potentiometer) for feeding back the position, and the disadvantage is that the number of seedlings becomes multiple. was there.

On the other hand, in recent years, with the digitization of circuits, an incremental encoder 5 is used as a one-position detector as shown in Fig. 2, and the pulse train generated by this is subtracted from the target value by an up-down counter. DA
By adding it to the converter 8, a position feed bank loop is formed, and by using the rising and falling pulses of the pulse train, the pulse generating circuit 6 generates a speed pulse train with a frequency proportional to the speed, which is then converted into a speed pulse train ( The search mechanism, which is used as a check signal, came into use.

In the latter method, a speed pulse train signal with a frequency proportional to the speed is used as a speed signal equivalently proportional to the speed by the low-pass filter characteristics of the amplifier 1 and motor 2 systems, and when the motor speed is high, the analog signal is used. Shows the same effect as that.

However, amplifier and motor systems have high-order AL transfer function characteristics, have a large phase delay at high frequencies, and in many systems, nonlinear Coulomb friction acts as a frictional force, and the machine 41Vl element acts as a load. Since the offset force having elasticity acts on the system, it becomes a welder robot system when approaching the positioning target value, and has the disadvantage of generating self-excited vibrations due to velocity pulses.

[Purpose of the invention]

The present invention was made in order to eliminate such drawbacks, and has the following object: to provide a highly stable positioning device that prevents self-excited vibration and has a good positioning angle of 1'17 degrees. What should I do?

[Summary of the invention]

In order to achieve such an object, the present invention provides a circuit for detecting the deviation of the output displacement from the target value and a circuit for delaying the output signal for a certain period of time, and detects the end of the operation to indicate that the output displacement has settled and stopped near the target position. This is characterized in that the progress loop gain is reduced by the signal to prevent self-excited vibration.

[Embodiments of the invention]

In general, a control system model for determining the target value of a positioning servo system using a motor having an elastic load, Coulomb Jcf, +mi, encoder, and speed pulse generation circuit can be represented by the block diagram in FIG. 3(a). Here, the tensile load is 101
, Coulomb friction corresponds to block +02, encoder corresponds to block 103, and speed pulse generation circuit corresponds to block 10/I. Although the encoder is a step-like function, it can be regarded as a relay element at minute displacements near the target value A4. Now pH the turron rub
5t, the system is composed of non-linear relay spinning as shown in 31st J(1,) and a higher-order system of 3,1 process shapes, and is described by the function method as an autoj-mass system shown by A. Stability determination becomes possible. In this system, the gender equation can be expressed as 1+N (E) G (j W) =0. However, N (IΣ): Descriptive function of the relay element G (j\v): Transfer function of the system According to the Nyquist stability criterion, in Fig. 3 (C), the amplitude locus of the relay element -1, /N ( E) corresponds to the negative real ΦIIth 5J and is the intersection point A with the frequency locus G(jw)
Self-excited vibrations can exist at

However, in an actual system, Coulomb friction exists, so if the gain of the frequency locus at the intersection with the amplitude locus, that is, the loop gain, is sufficiently small as shown by the broken line in Figure 3 (C), the energy will be equal to the friction; It is absorbed and the vibration does not last. (Point B). Here, the loop gain is determined by the gain of the amplifier and motor system, the position feedback gain, and the speed gain, and what is adjustable is the position and speed gain - the grasshopper gain. However, the former is the positioning accuracy and deceleration characteristic, and the latter is the response 1. The optimum value is determined by the 〒 property, and depending on the system, the loop gain becomes large, and for the above-mentioned reasons, self-excited vibration is generated after positioning, which can be a source of noise. Not only that, but it also shortens the life of the device. In such a case, if the loop gain is set to satisfy stability, positioning accuracy and responsiveness will deteriorate.

In order to satisfy dual positioning accuracy, responsiveness, and stability, the present invention increases the loop gain in the operating state to improve responsiveness, and decreases the loop gain in the stopped state to improve stability. There are characteristics. The loop gain reduction method reduces the velocity feedback gain without changing the position feedback gain that determines positioning accuracy. In addition, gain switching is performed so that the output displacement is within the specified positioning accuracy so as not to reduce responsiveness during positioning operation, and the deviation from the target value is a constant value of 1 (since it is performed after a constant stop). The circuit consists of a circuit that detects that the speed is within the range of 1 to 2, a circuit that delays the detection signal for a certain period of time and issues an operation end signal, and a circuit that reduces the speed feedback gain using the operation end signal.

FIG. 4(,) shows the configuration of an embodiment of the positioning device according to the present invention.

In the figure, a digital target value 21 is connected to an up/down counter 7 operated by a position pulse signal 27, and a deviation signal, which is an output signal of this counter 7, is passed through a D/Δ converter 8, a log amplifier 9, and a power amplifier 1. Manual power is applied to motor 2. Here, the position pulse signal 27
is a signal obtained by applying the two-phase pulse signal 26 of the encoder 5 connected to the shaft of the motor 2 to the logic circuit 10 as shown in FIG. 11(1). Further, the velocity feedback signal 29 is generated by transmitting the position pulse signal 27 through the velocity pulse generation circuit 6 and the gain reduction circuit 11. Here, the gain reduction circuit 11 outputs a signal 23J3 and a signal 23J3 outputted through the deviation detection circuit 2 which detects that the deviation is within 60 from the deviation signal 22.
Time d's slow misfortune W +
It is operated by the output signals 3, 1, 2, and 25.

According to the embodiment of the present invention shown above, the output deviation is Δ
When the signal 23 is output within 0, the operation end signal 25 is output after a time ']'d, and the IL, speed feedback signal 21] is low; When it becomes larger than 80, the operating signal 25 is turned off by the response signal 24, and the speed fee I is increased without being reduced, but the response rate is not impaired.

In the above implementation (σ), the gain reduction circuit 1j was designed to reduce the amplitude (・h) of the output pulse 28 of the speed pulse generation circuit 6, but by making it a circuit that shortens the pulse width, You can enjoy valuable effects.

〔Effect of the invention〕

As described above, the present invention provides highly stable positioning with good responsiveness and positioning accuracy.

[Brief explanation of drawings]

Figures 1 and 2 are block diagrams of a conventional positioning device, and Figures 3 (,) and (b) are diagrams showing a control system model of the positioning servo system near the 1'' target value (J) and its Q5' characteristic. , FIGS. 4(a) and 4(b) are a configuration diagram of an embodiment of the positioning device according to the invention and an explanatory diagram of its operation. j...Power amplifier, 2...Motor, 3... Tacho generator, 4...Position 1 disaster 3):, 5...Encoder, 6...Speed pulse signal generation circuit, 7...Counter, 8...D/A converter, 9... Log amplifier, 10...Logic circuit, II...Fast skin feedback signal low; Thief circuit, 12...Deviation comparator, 13...Delay circuit, 21...1" Target value, 22... Deviation signal, 2
3...Believing the output of the 11 deviation ratios, 24...Signal to delay circuit resetter 1, 25...Operation end signal, 26...Two-phase pulse signal, 27...Believing position pulse, 28...・
Speed pulse signal, 29...speed feedback number,
101...Elastic load element, 102...Coulomb I!
i! I-printing element, 103...Relay element, ], 011
...Pulse generation is necessary. Figure 1 S Figure 2 Figure 3 (θ,) <b) (C)

Claims (1)

[Claims] 1. In a positioning device consisting of a servo machine tlW that performs speed feedback using a pulse train signal with a frequency proportional to speed, a detection means for detecting that the output displacement is within a predetermined range with respect to a target value. A positioning device comprising: a delay means for delaying a detection signal of the detection means for a certain period of time; and a gain reduction means for reducing a velocity feedback gain by an output of the delay means. 2. The positioning device according to claim 1, wherein the gain reduction means is a means for reducing the amplitude of the pulse train signal. 3. The positioning device according to claim 1, wherein the gain reduction means is means for shortening the pulse width of the pulse train signal.